Method of treating tobacco and treated product



Patented Dec. 4, 1951 METHOD OF TREATING TOBACCO AND TREATED PRODUCTErnest C. Crocker, Belmont, Mass, assignor, by

mesne assignments, to Gustavus W. Dyer, Danville, Va.

No Drawing. Application June '1, 1945 Serial No. 598,203

2 Claims. (CL 131-17) 1 This invention provides for the protection oftobacco from infestation by various forms of insect life, to which it issubject, especially during storage and aging operations.

When tobacco is picked, the leaves are tied up in bundles and thesebundles are then cured. In curing they are more or less dried out. Thepartially dry condition thus produced permits of easily shaking thebundles free from loose bits of stems, leaves and the like, as well asany adherent dirt or dust which may cling to them. They still containconsiderable moisture, however, when they enter the market. It istherefore customary subsequently to dry all tobaccos quite thoroughly,to render them uniform in this respect, in artificial driers. Suchdrying brings all of the leaves to a uniform and low moisture content.But this is usually too low for proper aging of the tobacco, which iseffected best when the tobacco has a uniform moisture content, of about11 per cent by weight. Accordingly, it is the customary procedure toinject steam into and around the dried tobacco, while it is in the formof dried,

shaken and cleaned bundles, spaced apart and hung upon horizontal poles,either in a closed chamber or in the open, as desired, until it acquiresa moisture content of about 11 by weight from the steam and moistatmosphere. The bundles are then taken from the poles and laid down inlayers in wooden tubs or tierces, which are stored (in suitablewarehouses for the aging of the tobacco), usually for a period of 2 to 4years, to mellow it by fermentation and aging.

Although the bundles of tobacco as thus prepared are usually sterile,the subsequent long period of storage affords great opportunity forinfestation by various forms of life, such as insects, moths, larvae andthe like. This is due to the fact that, in various forms of such insectlife, it is capable of penetrating through very small apertures in thecontainers, and some are specifically attracted to the tobacco leaf as asource of food or as a suitable medium for the development of theirlarvae, etc. Such infestation actually consumes considerable quantitiesof the tobacco leaf, when it occurs. But it also deteriorates thequality of much larger quantities so that it must be discarded. Itfurther generally degrades the quality of the entire tub or tierce oftobacco, which has been thus infested, including those portions whichmay not be directly reached or affected, so that it has to be accorded amuch lower grade than it originally had.

In both the preparation and use of tobacco it is essential to recognizethat it involves hand operations and personal contact closely analogousto that of food products. Accordingly, the surrounding conditions oftreatment as well as the condition of the product at all times are offirst consideration and importance and must be carefully observed andcontrolled.

By the present invention advantage is taken of the fact that after thesteaming treatment above described the tobacco as a whole is in asterile condition. It is accordingly an object to provide a treatment ofthe same whereby it shall remain sterile and free from subsequentinfestation, conveniently and economically, with safety to the operatorand user, and also with complete effectiveness upon the tobacco treated,until it is ready to be manufactured into final form for use. Otherobjects will appear from the following disclosure.

In general it is found that during the storage or aging of tobacco, solong as the moisture or water content is preferably maintained at about11% by weight, the initially sterile tobacco is substantially free frominfestation or mold' growth. But the tub or tierces, in which it ispacked and stored for purposes of aging in the wood, and under theaction of the moisture within and changing atmosphere without, graduallyopen up minute cracks. These form primarily between the staves but alsobetween the boards in the heads of the tubs. They are sufiicient topermit the entrance ofair and the escape of air and moisture, also theentrance of small insects, moths and the like which cause damage,especially in the outer layers of the tobacco which are thus exposed anddried. The thus dried portions of the tobacco are thereby renderedfavorable to the penetration of the tobacco moth into this outer layer,the laying of its eggs, and the development of larvae. The moistinterior tobacco appears to be quite resistant to such infestation butthe outer layer of air-dry tobacco is not.

To protect this outer zone of the tobacco in each tub or tierce,therefore (which thus becomes subject to drying and infestation duringaging),

it is found to be sufficient to provide it with an atmosphere containingcertain chemicals which are volatile and in an amount which will beeffective and remain effective throughout the period of aging,collectively or severally but without being deleterious to thosehandling and treating the tobacco or to those using the tobacco.

In carrying out the invention in actual practice, those portions of thetobacco which during storage may be or become drier (than 11% moisture)and in which there may be an opportunity for infestation by insects. an.provided with a quantity of the liquid organic chemical. This ispreferably an organic compound characterized by containing oxygen andchlorine. It must be effective to destroy the insects which infesttobacco in the dry condition of storage, in extremely low concentrationsin the atmosphere. It must be non-toxic to those handling the productduring treatment, during storage and upon taking it from storage. Itmust be sufficiently volatile to permeate uniformly through theatmosphere of the charge treated therewith and yet remain within thetobacco and container throughout the long periods of storage and aging-2to 4 years-and be free from corrosion or decomposition to form corrosiveby-products, with respect to the tobacco or its container. It must bereadily evaporated and removed from the container and the tobacco uponbeing removed-from storage and exposed to the open atmosphere. It mustbe relatively inodorous as well as non-toxic in the concentrationsemployed, or, more especially, in the treated product after removal fromstorage and airing, and as it is put into final form for use, as incigarettes or packaging for consumer's use as pipe tobacco, or the like.After much experimentation it is now found that the chlorinated ethers,as a class, are well suited for these purposes, and more particularlychlorine substituted ethers, which have vapor pressures at 30 C., from.05 to 1.0 mm. of mercury. For example, triglycol dichloride, which hasa boiling point of about 241 C., vapor pressure at 30 C. of .07 mm.;dichloro diisopropyl ether which has a boiling point of 187 0., and avapor pressure of .70 at 30 C., and dichloro diethyl ether, having aboiling point of about 178 C. and a vapor pressure of 0.8 mm. of mercuryat 30 C.

These chemical agents have been demonstrated to be completely andspecifically effective against infestation of tobacco which is dried andexposed to a relatively mild concentration of their vapors. Such aconcentration may be indicated by their partial vapor pressures, as from.05/760 to 1/760 or .0000658 to .0013 mol weight per mol weightequivalent of air (22 liters).

The treatment of the tobacco with this class of agents may be effectedby spraying a fine mist directly upon the tobacco after its preliminarydrying treatment, or it may be applied in the course of re-moistening.For example, it may be introduced into the usual moistening chambers,dissolved in the sprays of moistening water, or vaporized andinterjected with the steam used in this operation. In this way an evendistribution is effected, continuously and throughout the entire mass oftobacco which is subjected to the re-moistening treatment.

On the other hand, the tobacco may be remoistened in the usual way withwater or steam and then treated with the re-agent as it is packed intothe tubs or tierces for aging. In so doing, the tobacco could be packedaround the periphery of the tub or tierce, and then filled in thecenter. In this type of packing the outer layer of bundles of tobaccoleaves, placed around the sides and also those on the bottom and top,would be sprayed, while those packed in the middle portion of the tub ortierce would not need to be treated. For it is found that not only doesthe inside portion of the pack retain its 11% moisture throughout theaging period of two to four years, but that in such lots of simplyre-moistened tobacco, which have been freely attacked by insects, theypenetrate 4 only the dried portions of the tobacco, constituting theouter three or four inches of the charge of firmly packed tobacco. Itmay be said, therefore, that if this outer zone is completely protected,the inner portion of the charge will be safe from infestation.

However, it is usually practiced to lay the bundles into the tubs ortierces in layers about 4 inches deep.' In so doing, in accordance withthe invention, the outer bundles of each layer, or the complete surfaceof each layer, may be sprayed. If a dilute spray or brief spraying isemployed (or where a long period of aging is contemplated), eachindividual bundle of the tobacco leaves might be sprayed with the liquiddispersion. When such procedure has been carried out, it might beadvisable to spread out and completely air the bundles, upon removingafter aging, so as to permit complete vaporization and escape ofresidual excess reagent from each bundle of the mass.

A preferred way of applying the reagent, however, is to apply the samein a uniform spray or coating to the inside surfaces of the wooden tubor tierce, including all of the staves, the inside of the bottom and theinside of the top. This may be effected quickly and effectively with aspray gun of any usual type, followed by charging them with the tobaccobundles in the usual way, without further operation. In this way theinsecticidal reagent is uniformly applied and completely surrounds theentire charge of tobacco. It is thus in proximity to the entire outerzone of tobacco, which is most subject to drying and thus becomingsusceptible to insect attack, and throughout the area of the containerthrough which the insects, to reach the tobacco, must first penetrate.

A further adaptation of the latter procedure is to apply the organiccompound to the outer surface of a sheet of paper, such as parchment orother suitable sheet material, which is then inserted into the empty tubor tierce as a liner about the side walls and over the bottom (beforepacking), and then over the top of the tobacco, when the container isfilled. In this way, also, direct application of the compound to thetobacco leaves may be avoided, and no question of removing any excessfrom the tobacco after aging is involved. Especially is thisadvantageous in case, for example, the tobacco is removed after ashorter aging period than was originally intended and provided for inthe amount of chemical which was applied.

Tobacco packed and treated and stored for aging in these ways has beenfound to be completely protected against infestation, even thoughinsects in their various forms and stages were prevalent and actuallyinfested and destroyed or greatly lowered the value and grade ofadjacent tubs of the same kinds and qualities of tobacco, treated andstored in the same way, but without the chemical treatment of thisinvention. The saving, therefore, which is thus effected by the chemicaltreatment, by avoiding loss of tobacco by infestation, is not onlyrendered certain by the present procedure and of broad significance tothe tobacco industry, but of even greater importance and value inmaintaining the grade and quality of all tobaccos at the high levelwhich characterizes them when they are put into storage at thecommencement of the aging treatment.

For example, in treating tubs containing 500 pounds of tobacco each, anapplication of 3.50

ounces of dichloro-diisopropyl ether, by spraying over the successivelayers of tobacco as packed intothe tub, was completely effective inprotectme the entire contents of the tub from intestation for a periodof 16 months. By applying 3.0 ounces of triglycol dichloride to theinner surface of the wooden tub, followed by packing it with tobacco,the contents were protected from infestation for a -like period, whiletobacco in tubs, similarly packed without any chemical treatment, andaged under the same conditions for the same length of time, wasseriously infested by tobacco moths, larvae, etc., and the contentsgreatly degraded in quality. Moreover, upon removal at the end of theaging period, the treated tobacco was substantially without odor of thechemicals, either in the course of handling or subsequent use.

In general, the addition of a suflicient amount of chemical to vaporizeand develop its normal partial pressure in and throughout the atmosphereof the container (for each month 01 storage) is quite sufflcient toeffect and maintain the original conditions and concentrations undernormal operating conditions of wooden tubs and in the atmosphere oftobacco warehouses.

'Iclaim:

1. In the method of treating moisture containing tobacco, the step oftreating said tobacco with a liquid ether selected from the groupconsisting of triglycol dichloride, dichlorodiisopropyl ether anddichlorodiethyl ether in a container during storage for a timesufflcient to prevent intestation of said tobacco by insects.

2. Encased moisture containing tobacco having therein liquid etherselected from the. group consisting of triglycol dichloride,dichlorodlisopropyl ether and dichlorodiethyl ether.

ERNEST C. CROCKER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS a Number Name Date 923,165 Goldman June 1, 19091,213,129 Pack Jan. 16, 1917 OTHER REFERENCES A pamphlet entitledEntoma. A Directory oi Insect Pest Control. Fourth edition, published in1941. A copy is in the Virginia State Library, at Richmond, Virginia.The catalog number is S3951, E55, 1941. Page 52 and the table ofcontents are relied on.

Page 1150 of the "Country Gentleman" for July 10, 1915. A copy is in theLibrary 0! Congress at 30 Washington. D. C,

1. IN THE METHOD OF TREATING MOISTURE CONTAINING TOBACCO, THE STEP OFTREATING SAID TOBACCO WITH A LIQUID ETHER SELECTED FROM THE GOUPCONSISTING OF TRIGLYCOL DICHLORIDE, DICHLORODIISOPROPYL ETHER ANDDICHLORODIETHYL ETHER IN A CONTAINER DURING STORAGE FOR A TIMESUFFICIENT TO PREVENT INFESTATION OF SAID TOBACCO BY INSECTS.
 2. ENCASEDMIXTURE CONTAINING TOBACCO HAVING THEREIN LIQUID ETHER SELECTED FROM THEGROUP CONSISTING OF TRIGLYCOL DICHLORIDE, DICHLORODISOPROPYL ETHER ANDDISCHLORODIETHYL ETHER.